Teaching rates three decades ago seem near the same as today, which is shocking. I was first paid 100 Baht an hour in Bangkok so back then a hard working popular teacher could easily make 20K a month. That was standard bottom end and common. Many teachers made 30K, some 40K, some even more.
By chance my school closed, and while workmates scrambled to find work again, I said I would try to improve my image with a new necktie, better shirt, and importantly, overpriced Italian shoes. I asked for a thousand Baht an hour, and I got it. Two years later I was charging between 800-2,400 an hour depending on the students. Most importantly; I got results, kids learnt to use English, real working English language, and within just months.
Put your heart into it, make the time real, alive, fun, and personalize all of it, rewrite lessons as you go, adjusting to the moment. Just going through the standard steps of each lesson achieves little, compared to living real life activity. Playing games, laughing, competing, arranging and understanding stuff together, eating, cleaning up, behaving with emotion, it's all language development. When the students ask for more and tell thier parents they 'want to study', you will be appreciated and paid accordingly.
The shoes may have helped, probably helped me more than anything, but once it's working, it's so rewarding. Teaching is a great profession and although it may not appear easy; it can pay well. I used to teach just four days a week, but I worked hard and enjoyed it. My income back then was about 100K, sometimes quite a bit more. Choose your company carefully, many expats only ever get to know the lower working classes. There's a lot more to Thailand than streetside food sellers and taxi riders. Discover the normal working classes and beyond, it becomes much more interesting and lucrative.